Mental Processes in Man. 3 1 1 



the mere passive response in consciousness which we call 

 an impression, and more complex than that mental activity 

 which, through discrimination and recognition, converts the 

 bare impression into a sensation. It is, in fact, part of 

 that mental process which is called perception.* Sensa- 

 tion has nothing to do with the objects around us as such ; 

 it is by perception that we are aware of their existence. 

 Let us now follow the process of perception a little further, 

 always remembering that it involves certain activities of 

 the mind. 



These activities are too often ignored. We often speak 

 of the senses as the avenues of knowledge, and John 

 Bunyan, likening the soul to a citadel, spoke of the five 

 gateways of knowledge, Eye-gate, Ear-gate, Mouth-gate, 

 Smell-gate, and Feel-gate. Hence arises a vague notion 

 that through the eye-gate, for example, a sort of picture 

 of the external object somehow enters the mind. And this 

 idea is no doubt fostered by the fact that an inverted image 

 of the object is formed on the retina, though how the 

 inverted image is turned right way up again in passing 

 into the mind bothers some people not a little. f 



* I use this term in a broad sense, as the process involved in the formation 

 of what I shall term constructs. 



f And I may add it is not an easy matter to explain to those who have not 

 considered such questions. It is a matter of the correlation of the testimony 

 of the sense-organs. A hoy stands before me. I go to him and touch him, 

 and pass my hands downwards from head to foot. Then I stand a little way 

 off and look at him. His image on my retina is inverted. But as I run my 

 eye over him I direct my eye downwards to his feet and upwards to his head. 

 I am not conscious that the stimuli are running upwards along the retinal image. 

 Thus my eye-muscles and my other muscular and tactile sensations seem to tell 

 me that he is one way upwards. The image on my retina tells me, though I am 

 not conscious of the fact, that he is the other way upwards. But he cannot 

 be both ! The testimony of one sense has to give way. One standard or the 

 other has to be adopted. Practically that of touch and the muscular sensations 

 is unconsciously selected, and sight-sensations are habitually interpreted in 

 terms of this standard. So long as the two are sufficiently accurately 

 correlated, the practical requirements of the case are met. And it is well 

 known that it is not difficult, with a little practice, to establish a new correlation. 

 This is indeed done every day by the microscopist, for whom the images are 

 all reversed by his instrument. He very soon learns, however, that to move 

 the object, as seen, to the left, he must push it to the right. Anew correlation 

 is rapidly and correctly established. 



